This invention relates to smoking articles such as cigarettes.
In the manufacture of smoking articles such as cigarettes, design parameters can be varied in order to control properties thereof. For example, properties such as the tobacco smoke delivery profile can be varied in order to control the composition of the tobacco smoke during use of the cigarette. Typical parameters which are varied include the choice of tobacco additives and/or cigarette paper additives, the permeability of the cigarette paper, the composition of the tobacco or blend of smokable materials, the strand width of the smokable material, the filling capacity of the smokable material, the properties of the filter element which is employed, and the like.
An ability to change the smoke delivery profile of the cigarette allows the manufacturer to provide cigarettes exhibiting varying perceived sensory characteristics. Such characteristics can be varied from cigarette to cigarette and/or from puff to puff during use of a particular cigarette.
One particularly useful method for providing cigarettes having unique smoke delivery profiles involves manufacturing cigarette rods having various segments of smokable material wherein each of the various segments are defined in terms of their densities. For example, a cigarette rod can have a region of smokable material of substantially uniform but relatively high density extending along a portion of the length of the rod towards the mouthend or filter end thereof, and a region of smokable material of substantially uniform but relatively low density extending along a portion of the length of the rod towards the fire end or lit end thereof. Although such a cigarette rod can provide a unique puff-by-puff delivery to the smoker, the burn characteristics thereof may not be as controllable as may be desirable. For example, a cigarette having a low density region of smokable material towards the fire end thereof may tend to burn initially at a relatively fast rate, while the dense region of smokable material positioned towards the mouthend or filter end thereof may tend to burn at a relatively slow rate. Thus, such a cigarette may tend to burn down relatively fast and then relatively slow, during the time that the cigarette is smoked.
It would be highly desirable to provide a cigarette rod which is capable of being manufactured such that the smoke delivery profile and the burn rate thereof can be readily controlled.